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Homing question

PostPosted: Fri Jan 20, 2017 10:44 am
by svse
Hi everbody,

my name is sven from germany.
I have updated my Frieda-CNC from LinuxCNC and Parallelport to the UC400Eth with UCCNC a few days ago.
The installation of the Software and the UC400 is really easy. Thanks for that!

But at the configuration i am a little bit confused.

I want the homing sequence behaviour similar to the linuxCNC homing.
At LinuxCNC the axis drives to the homing switch with a middle speed, triggers it, went back a few mm, then triggers it again with low speed, than went back to a defined position.
Is it possible to get the same in UCCNC? With a macro?
The Homing button let the axis triggers the switch one time and then went back. Is it possible to define this distance to the switch? What is the distance to the switch?

Another point: In the configuration is the point "write offset on homing". If I activate the softlimits, the "write offset on homing" could not be smaller than the "softlimit-", if auto set is activated.
For example: (homing switch is limit switch) Position of homing switch is -15mm (write offset on homing should be -15mm), softlimit- : -10mm. Then the sw corrects the "write offset of homing" to -10mm. Why?
I want to have a safety zone between the softlimit- and the limit switch.

Kind regards,

Sven

Re: Homing question

PostPosted: Fri Jan 20, 2017 12:15 pm
by cncdrive
I want the homing sequence behaviour similar to the linuxCNC homing.
At LinuxCNC the axis drives to the homing switch with a middle speed, triggers it, went back a few mm, then triggers it again with low speed, than went back to a defined position.
Is it possible to get the same in UCCNC? With a macro?
The Homing button let the axis triggers the switch one time and then went back. Is it possible to define this distance to the switch? What is the distance to the switch?


The UCCNC works different, it has a homing up and down velocity parameters.
The upgoing parameter is when the axis is moving on the switch.
And the downgoing parameter is when the axis is moving off the switch.
The home coordinate is registered when the axis is moving downwards and when the switch deactivates.
So, the up speed can be high so the axis can reach the home switch fast and the down speed can be slow, so the registered position will be precise.

Another point: In the configuration is the point "write offset on homing". If I activate the softlimits, the "write offset on homing" could not be smaller than the "softlimit-", if auto set is activated.
For example: (homing switch is limit switch) Position of homing switch is -15mm (write offset on homing should be -15mm), softlimit- : -10mm. Then the sw corrects the "write offset of homing" to -10mm. Why?
I want to have a safety zone between the softlimit- and the limit switch.


This is because you can't move over the software limits, so defining a more far point makes no sense and the software knows that.
There is no safe zone in the UCCNC, because the motion controller continously calculating and automatically slows down on the softlimit point,
so if the axis travels at a feedrate towards the softlimits coordinates then the axis will start to slowdown to stop on the softlimits point with the set acceleration.

Re: Homing question

PostPosted: Fri Jan 20, 2017 2:21 pm
by svse
thanks for the fast reply,

thats nice to know, that the homing point is where the axis is going off the switch. I didnt know yet.

For the second point, i will test it with softlimit- same as "write offset on homing" and see what happens.

Greetings, Sven